Carburetor for internal-combustion engines



F. F. STRATTON. v CARBURETOR FOR INTERNAL COMBUSTION ENGlNES.

APPLICATION FILED MAR. 18, 1918- 1,403,987.

Patented Jan. 17, 1922.

2 SHEETS-SHEET 1-- F. F. STRATTON. CARBURETOR FOR INTERNAL COMBUSTIONENGINES.

APPLICATION F'ILED MAR. 18, ms. 1,403,987, Patented Jan. 17, 1922..

2 SHEETS-SHEET 2 UNITED STATES PATENT OFFICE.

CARBURETOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed March 18, 1918.

To all whom it may concern:

Be it known that I, FENToN FREDERICK STRATTON, a subject of the King ofGreat Britain and Ireland, and a resident of Oak Lodge, Park Hill Road,East Croydon, Surrey, England, have invented new and useful Improvementsin Carburetors for Internal- Combustion Engines, of which the followingis the specification.

The objects of this invention are to provide better means for feedingthe correct rel ative proportions of liquid fuel and air to the engine,and to better control the supply of mixture to the engine under allconditions of running. j In this invention I provide an automatic valvesimilar to that described in my prior specifications Serial Nos. 117,095and 184,- 952, adapted to move vertically upward in the carburetor whenoperated by the suction of the engine and to move downwardly in thecarburetor by the action of gravity assisted or not by a sprin the saidautomatic valve in rising being a apted to open ports formed in the wallof the carburetor to admit air; there may be one port for each liquidfuel jet brought into operation.

According to my invention I provide in combination with the saidvalve,members constructed as hereafter described which not only operate ascaps, that is to say, to close over the jet or nozzle until itscorresponding air port has been opened by the automatic valve, but alsoto a certain extent as choke tubes for each said jet. I suspend orsupport the combined cap and choke tube from a lug or the like securedto or integrally formed with the said valve in such manner that whilethe cap serves on rising to bring the jet into operation, the choke tubeintegrally formed with the cap provides a progressively increasing areafor the passage of air to correspond with the rise of the valve.

In forming the choke tube integrally with the cap I provide one or morelongitudinal slots in the side of the cap preferably on opposite sidesof the cap, and preferably so arranged one a little higher than theother that air shall not only pass through the choke tube to sweep theliquid fuel issuing from the end of the jets through the said slots, butalso that air passing upwardly through the body of, the carburetor whenthe port of that jet is fully open shall deflect through the lower ofthe said slots to sweep Specification of Letters Patent.

Patented Jan. 17, 1922.

Serial No. 223,212.

across the top of the jet and through the higher of the two said slots.

I provide on the base plate of the carburetor of the kind I havedescribed in my said prior specifications, an annular centre or ringprojecting above, but formed integrally with the said base plate, whichring is adapted to fit and hold centrally the choke tube of the centralpilot jet, and I form through the said annulus small holes for thepassage of air from the outer annular chamber to the said choke tube.

The above described construction is ap plicable to a carburetor in whichone liquid fuel only is employed, petrol for example, or one in whichtwo liquid fuels are employed with two float chambers, petrol andparaffin for example, in which the petrol is supplied to the pilot jetonly, and parafiin to the main jets only, and it is for use with twoliquid fuels that the invention is preferably employed, and it is asadapted for such use that the invention is shown in the accompanyingdrawings.

Fig. l is a sectional elevation through the centre of the improvedcarburetor in the plane of the jets. In the example of the inventionshown, only two jets are employed for the heavier liquid fuel inaddition to the central jet used for starting purposes and employing alighter liquid fuel such as petrol or the like.

Fig. 2 is a sectional plan of the improved carburetor.

Fig. 3 is a vertical section of the base plate.

Fig. 4. is a plan of same.

Fig. 5 is a sectional elevation of the jet chamber and valve cylindershowing two of the air ports therein. 7

Fig. 6 is a sectional elevation of choke tube of the pilot or startingjet.

Figs. 7 and 8 are sectional elevation and elevation respectively of thenew construction of cap which also acts partly as a choke tube.

A is the central cylindrical casing containing the jet chamber havingintegrally formed therewith the second cylinder B of larger diameter. Cis a sliding pisto of two diameters, the larger of which is adapted toslide or reciprocate loosely within the cylinder B, the inner or smallerdiameter being formed as a hollow sleeve or extension C The smallerdiameter of the piston valve rises.

F which cover of the chamber removed.

valve C is adapted to very loosely fit and slide within the smallerdiameter of the central cylindrical jet chamber A. The piston valve C isopen. to the suction of the engine ilo. 184,952, these air ports arearranged in.

stepped relation in order that they shall be opened successively andprogressively as the In the construction or example of the inventionshown, there being only. two main jets provided, these ai-r ports D arearranged in the cylindrical wall of the chamber A at the same level.

E is the pilot jet for lighter liquid fuel enclosed within the choketube F. The choke tube F is provided at the upper end with a centralportion of reduced diameter permanently throttles, owing to this reducton in diameter, the air supply passing through the tube F. The air supply is fed to the tube F from the chamber A through the four radialchannels F shown dotted in plan, Figs. 2 and 4. These are boredhorizontally through the annular centre or ring G projecting above butformed integrally with the base plate G, the tube F fitting within acentralrecess within the said ring G but not covering the said channelsF so that air may pass by the said radial channels F 2 to form thestarting mixture by means of the lighter liquid fuel from the jet Ebefore sufiicient suction or vacuum effect is produced by the engine toraise the automatic valve C.

i H and I are the two main jets for the supply, in the example shown, ofthe heavier liquid fuel such as paraffin. These are screwed intobifurcated passages H I formed in the base plate G and connected to thechannel or passage J communicating directly with the float chamber J ofordinary construction supplied with a heavier liquid fuel such asparaifin.

The central jet F is screwed into the end of the channel F 4 (see Figs.2, 3 and 4) which is in communication with the fioat feed chamber K,containing a supply of the lighter liquid fuel such as petrol, shownwith the cap or cover L which is centrally fitted or suspended over themain jet H is supported r or suspended from the automatic valveC as pinholes L the securing pin L being removable in order to fit in one of theholes The cap .or

L This provides for adjustment of the cap relatively to the valve fromwhich it is suspended with relation to the jet H. The cap. M issimilarly fitted over the other jet I for heavier liquid fuel. The capsL and M are each formed with a bell mouth L h 2 respectively at thelower end, see Figs. 7 and 8; they are also provided withlongitudinalslots indicated by the letters L L* in Fig. 7, and by M M in Fig. 8. Ineach cap one of the slots is placed at a higher level than the other. 7v Referring to Fig. 1, the base plate G is formed with an annularshoulder on its lower surface on which fits the flanged casing Nprovided at its centre with a screwed edge upon which the union nut O issecured. The nut O carriesthe elbow connection P by which heated air isconveyed tofthe'carburetor through the ports Q R S in the base plate G.p

The throttle valve shown is of ordinary construction.

The carburetor operates as follows hen the engine is started and thesuction of the engine produces a negativepressure in the carburetor, theautomatic valve is closed, air is drawn through the pipe 'P and theports (3, R S into the annular chamber T, and thence .through the radialchannels F to the choke tube F. Liquidfuel is supplied from the jet Eand the starting-mixtureis conveyed by the reduced channel F to theengine. lVhen the engine has gathered speed sufficiently and the vacuumeffect increases, the valve 0 rises opening the air ports I).Simultaneously the caps L, M, in rising permit the passage of airlongitudinally up the cap to a certain extent and fuel is fed from thejets H, I. As the valve rises farther and lifts the caps fartherrelatively to the jets more air passes through each cap acting as achoke tube. :The air and liquid fuel issuing from the jetspassesupwardly and outwardly through .theslots L L, and M M At the same timethe valve rising farther and having attained approximately its maximumlift the air ports .1) are fully opened and the air in passing throughthe chamber A tends also to sweep across from the lower slot L to theupper slot L in the .onecap and the lower slot M to the upper slot M inthe upper cap andto sweep therewith the liqu d 'fuel issuing'from eachof-the jets H and I, to form mixture which passes outwardly by thethrottle at the upper end of .the carburetor to the engine;

It will be understood that the flow! of petrol from the nozzle Euceasesor nearly .cea ses*when the lighter fuel feeding'nozzles come into playsince when the air ports D are opened by the lengtheningof-the valve,,air is so freely admitted to the, inside of the carburetor that thesuction practicallyceases upon the jet E, this being due to a greatextent to the contracted area in the channel in the top end F.

lVhat I do claim as my invention and desire to secure by Letters Patentis In a carburetor, a casing provided with an air intake port, aplurality of jets, a piston reciprocable in the casing and operated bythe engine suction, tubular caps for the jets carried by the piston,each of said caps being constructed and arranged to slide over one ofthe jets, the caps being adapted to receive air at their lower ends, andeach cap being closed at its upper end and having a pair of air portsintermediate the ends FENTON FREDERICK STRATTON.

Witnesses:

I. D. Roo'rs, M. MELLOR.

